The map position of the sur mutation (suppression of rho defects) will be determined with respect to the outside markers ilv and rbs on the genetic map of the bacterium Escherichia coli. Rho protein will be purified from rho mutant cells, rho sur double mutants and rho controls. The enzymological activity of rho ATPase and the tryptic digest pattern of rho from each strain will be compared, to determine if the sur mutation results in alteration of rho. The physiology of strains carrying rho-ts15 will be determined to elucidate the basis of a conditional methionine auxotrophy, especially to test the hypothesis that rho-ts15 results in transcriptional readthrough into inappropriate translational initiation signals on adjacent operons. Wild-type rho protein will be purified in large quantity to be used to prepare rabbit anti-rho antibody. The possibility of the presence of rho in two other bacterial species, Bacillus subtilis and Erwinia caratovara will be investigated, and if rho is found it will be used in heterologous and homologous systems of DNA and RNA polymerase. A procedure to isolate mutants of E. coli with temperature-sensitive rpoA mutations (alpha subunit of RNA polymerase), that result in temperature-sensitive RNA polymerase will be improved and applied in large scale.